1. Field of the Invention
This invention relates to a novel polysaccharide having glucose as the main constitutive sugar thereof, the bonding mode thereof being .beta.-linkage the principal chain being of .beta.-1,3 linkage the non-reducing end-group thereof branching at .beta.-1,6 linkage 38.0 to 43.0% thereof being the non-reducing end-group, and further containing 4.0 to 6.0% of phosphoric acid and more particularly to an extracellar, cell wall polysaccharide produced by an Fungi Imperfecti (deposited at Biseibutsu Kogyo Gijutsu Kenkyusho, Deposite No. 4257) belonging to the genus of aureobacidium in the family of black fungi.
2. Description of the Prior Art
In the course of a research for polysaccharides contained in raw sugar, the present inventors isolated a strain belonging to the genus of aureobacidium having strong kaolin aggregation activity. They compared the isolated strain with scores of different kinds of known strains belonging to the genus of aureobacidium or that of pullularia to find that the isolated fungus was strongly productive of kaolin agglutination activity. They established a method for culturing the isolated fungus. Further, they conducted studies for utilization of this substance as agglutinating agent. Eventually, a method for the manufacture of the agglutinating agent and a method for the utilization of the same were developed as disclosed in Japanese Patent Application No. 121687/1977 and No. 097664/1978. A food modifying agent was further developed as disclosed in Japanese Patent Application No. 007816/1979.
The agglutinating agent prepared by using the above stated isolated fungus (deposited at Biseibutsu Kogyo Gijutsu Kenkyusho, Deposite No. 4257 and at American Type Culture Collection, Deposit No. 20524, i.e., ATCC No. 20524) has come to be manufactured on an industrial production scale for practical use. The present inventors gave attention to the physicochemical properties of this actively agglutinating substance, such as high viscosity, nonadhesiveness, unique agglutination with aluminum ion, jellification of an ethanol solution and formation of an insoluble matter by acid hydrolysis. They isolated the effective component of the actively agglutinating substance and conducted analysis on the physical and chemical structure thereof. It was thus found that this effective component was a polysaccharide. This was a novel polysaccharide which had glucose as the main constitutive sugar thereof, the bonding mode thereof was such that the principal chain was .beta.-1,3 and 38.0 to 43.0% thereof was a non-reducing end-group branching at .beta.-1,6. The polysaccharide further contained 4.0 to 6.0% of phosphoric acid group and liberated an acid matter when subjected to an alkali treatment. This finding has led to the present invention. In the meantime, polysaccharides of .beta.-1,3 linkages has recently come to draw public attention as anti-tumor polysaccharides.